From the U.K., a comprehensive epidemiology of common complaint in the elderly.

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Symptomatic midfoot osteoarthritis (OA) is common in community-dwelling older adults and is particularly common among females in the lower socioeconomic classes, in a study from the U.K.

Evidence indicates a central role for mechanical load, including obesity, in this phenotype.

Symptomatic midfoot osteoarthritis (OA) is common in community-dwelling older adults and it is particularly common among older females in the lower socioeconomic classes, a cross-sectional study from the United Kingdom has found.

Investigators led by Martin Thomas, MD, Keele University, Keele, Staffordshire, England, found that symptomatic midfoot OA was present in 12% of the population over the age of 50 years (95% CI 10.9-13.2) while disabling symptomatic midfoot OA was present in 9.6% of the same population.

However, among females 75 years of age and older, the presence of symptomatic midfoot OA was 16.6% and the presence of disabling symptomatic midfoot OA was 15.3%.

Compared with prevalence rates of 6.9% and 4.9% of symptomatic and disabling symptomatic midfoot OA among the managerial and professional classes, rates of both symptomatic and disabling symptomatic midfoot OA were at least twice as high among those in the intermediate socioeconomic class at 12.6% for symptomatic midfoot OA and 10.5% for disabling symptomatic midfoot OA.

The prevalence of symptomatic and disabling symptomatic midfoot RA was also twice as high among those with routine and manual occupations, at 13.3% for symptomatic and 10.5% for disabling symptomatic midfoot OA, respectively.

"The foot has largely been neglected relative to other sites commonly affected by OA," Thomas and colleagues wrote in Arthritis, Research & Therapy.

"And in this U.K. study, we provide the first comprehensive account of the descriptive epidemiology of symptomatic midfoot OA."

The group used baseline data from a population-based prospective observational cohort study, the Clinical Assessment Study of the Foot (CASF), upon which to base their analyses.

Adults 50 years of age and older registered with 4 general practices in North Staffordshire were invited to take part in the study. In total, 525 patients contributed to the final analyses.

At baseline, eligible participants were mailed a health survey to elicit symptoms of foot pain in general.

Those who reported having foot pain in the last 12 months were invited to attend a research assessment clinic where weight-bearing dorsoplantar and lateral radiographs of each foot were done along with a clinical interview and physical examination.

Midfoot pain was defined as self-reported pain in the last 4 weeks and was identified by asking participants to shade the affected region on a foot model.

Symptomatic midfoot OA was defined as a radiographic score of 2 or more for osteophytes or joint space narrowing on either weight-bear dorsoplantar or lateral views in one or more midfoot joints: the 1st or 2nd cuneometatarsal (CMJ); the navicular first (NCJ), cuneiform and talonavicular joints (TNJ) and midfoot pain the last 4 weeks in the same foot.

Disabling symptomatic midfoot OA was defined as symptomatic radiographic OA together with at least 1 of the 10 items within the MFPDI function construct scored at the level of "on most/every day(s)."

"The population prevalence of midfoot pain in the last month among adults aged 50 years and over was 19.4% (95% CI 18.3-20.5%)," the authors note.

Among clinic attendees, 149 individual feet were diagnosed with symptomatic midfoot OA and of those, 67% had only 1 joint involved, the 2nd CMJ being the most commonly affected followed by the TNJ joint, the 1st CMJ and then the NCJ.

As the investigators noted, symptomatic midfoot OA was positively associated with body mass index (those with a BMI of ≥30 kg/m2 having twice the risk of symptomatic midfoot pain at an adjusted odds ratio of 2.20 (95% CI 1.32-3.08).

Those with symptomatic midfoot OA were also more likely to recall having sustained a previous injury to either the foot or ankle at an adjusted OR of 1.60 (95% CI 0.98-2.60) than those who did not recall having a previous foot or ankle injury.

In contrast, those who recalled frequent vs low use of high-heeled footwear were not more likely to have symptomatic midfoot OA (adjusted OR 0.98, 95% CI 0.51-1.88).

Furthermore, the proportion of participants who had consulted a general practitioner about foot pain in the previous 12 months was high at over 46% while 18.5% had consulted a physiotherapist and almost 48% had consulted a podiatrist or chiropodist.

Some two-thirds of respondents also reported using some form of oral analgesia in the past month for foot pain with roughly equal percentages taking paracetamol, mild to moderate opioids or non-steroidal anti-inflammatory drugs.

As the investigators noted, the clinical sample all had foot pain in the last 12 months, suggesting that prevalence estimates represent symptomatic individuals and all the associations were relative to foot pain elsewhere.

"Consequently, the observed association may underestimate the true effect," they suggested.

Other limitations included the fact that estimates for previous injury, previous use of footwear, and healthcare use were all based on self-reports and thus may not be wholly reliable.

And, the selected healthcare use estimates were based on small numbers and therefore could only be estimated imprecisely.

"For the local management of symptomatic midfoot OA, there is limited evidence for interventions such as foot orthoses, intra-articular corticosteroid/local anesthetic injections and arthrodesis," the authors wrote.

"Better characterization of this phenotype may help to inform more effective targeted treatments."

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